Axially laminated synchronous reluctance motors have been shown to be highly efficient with high power factor and power densities. Known techniques for producing rotors for such motors include using anisotropic grain oriented steel with multiple laminations made in segments and assembled to a rotor machine from fiberglass. Segments are interleaved with aluminum sheets to provide transient torque to damp any oscillation during transience and provide some mechanical integrity to the segments. This manufacturing technique is expensive and limits the use of high efficiency motor to special applications where cost is warranted.
As an alternative to the use of steel laminations for magnetic cores, it has been suggested that cores can be formed from iron powder. An article in Powder Metallurgy, Volume 25, No. 4 (1982), Pages 201-208, entitled "Properties and Applications of Soft Magnetic Powder Composites" authored by Kordecki, Weglinski and Kaczmar, discloses magnetic cores that are formed of ferromagnetic powder. This article discloses so-called magneto-dielectrics that are comprised of iron powder and a dielectric.
Prior art soft magnetic powder composite structures have exhibited direct axis to quadrature axis reactance ratios as high as 4, and some as high as 6.
United States patents describing the use of powdered iron structures in dynamo-electric machines include U.S. Pat. Nos. 4,947,065, 5,004,577 and 5,121,021.